Generally the buttonhole stitched by sewing machines is composed of first bar-tack stitches, left side line-tack stitches, second bar-tack stitches and right side line-tack stitches. Heretofore, it has been necessary for the machine operator to manually adjust the buttonhole stitching device of the sewing machine each time at the termination of stitches of the four stitch processes of the buttonhole. At least it has been necessary for the machine operator to manually adjust the buttonhole stitching device two times for stitching the first half and the second half of the buttonhole. Further the machine operator must measure the size of a button before the buttonhole is stitched, so as to make the formation of a buttonhole in accordance with the button to be employed. Depending upon the manual adjustment of the sewing machine, it may happen that the stitched buttonhole is large or small for the size of the button. In any event, according to the prior art, it has been difficult or troublesome to stitch a buttonhole with a sewing machine. Especially manual operation of the sewing machine during stitching a buttonhole has produced various disadvantages for the machine operator.
The present invention has been devised to eliminate such disadvantages of the prior art. Namely it is the fundamental object of the invention to provide a system in a sewing machine for easily setting the size of a buttonhole in accordance to a button to be employed.
It is a second object of the invention to provide a sewing machine for automatically stitching all stitch processes of a buttonhole.
It is another object of the invention to provide a system for electrically controlling the buttonhole stitching operation of a sewing machine, and especially adapted to be used in an electronic sewing machine.